Python is missing from the default ubuntu-22.04 runner image, which
prevents git-p4 from working. To install python on ubuntu, we need
to provide the correct package names:
* On Ubuntu 18.04 (bionic), "/usr/bin/python2" is provided by the
"python" package, and "/usr/bin/python3" is provided by the "python3"
package.
* On Ubuntu 20.04 (focal) and above, "/usr/bin/python2" is provided by
the "python2" package which has a different name from bionic, and
"/usr/bin/python3" is provided by "python3".
Since the "ubuntu-latest" runner image has a higher version, its
safe to use "python2" or "python3" package name.
Helped-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com> Signed-off-by: Jiang Xin <zhiyou.jx@alibaba-inc.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>